PROPOSED PROGRAM (Adapted from Applicant's Abstract) The long-term objectives of this Program Project application are to evaluate basic mechanisms and develop new treatments for acute lung injury. High concentrations of oxygen and septic lung injury are the primary models that will be evaluated. The proposed program consists of four projects and three core units. Project 1 will evaluate the efficacy of small molecular weight catalytic antioxidants in the treatment of both hyperoxic and LPS + sepsis-initiated lung injury. This project will also develop new antioxidant mimetics and explore their relationships with the antioxidant properties of heme oxygenase (HO). Project 2 will test the hypothesis that activation of extrinsic coagulation and disordered fibrin turnover are central elements in hyperoxic and septic lung injury. The efficacy of specific blockade of the initiating steps of extrinsic coagulation in reducing inflammation and acute lung injury will be tested using two new anticoagulant drugs that block tissue factor (TF) function and do not cause bleeding. Project 3 will evaluate the regulation and function of the extracellular superoxide dismutase (EC-SOD) in acute lung injury and determine the impact of cleavage of the C-terminal "heparin binding" domain of this enzyme in determining its distribution and function. Project 4 will evaluate control of metabolic pathways and upregulation of lung cell glycolysis in modulating responses to acute injury. This project will test the hypothesis that adaptation to oxidant stress in the lung requires elevated expression of hexokinase (HK), a rate limiting step in glycolysis in the lung. The overall rationale for the Program Project is to use an interdisciplinary approach to define the cellular pathways and cellular adaptive responses involved in acute lung injury and to test new strategies for pharmacologic therapy that can be extended to the treatment of humans with ARDS and sepsis.